This invention is directed to bis(salicylaldiminato)titanium complex catalysts, and highly syndiotactic polypropylene makable therewith by a chain-end control mechanism, and block copolymers containing the syndiotactic polypropylene and poly(ethylene-co-propylene) and/or poly(alpha-olefin-co-propylene), as well as to living olefin polymers and to olefin terminated to oligomers and polymers and to methods of making syndiotactic polypropylene, block copolymers and olefin-terminated oligomers and polymers from propylene.
The kind of polypropylene in general use, for example, for packaging and container functionality, is isotactic polypropylene. It is typically described as having the methyl groups attached to the tertiary carbon atoms of successive monomeric units on the same side of a hypothetical plane through the main chain of the polymer. Isotactic polypropylene lacks clarity and thus is not useful in cases where this is important.
Another kind of polypropylene is syndiotactic polypropylene. It may be described as having the methyl groups attached to the tertiary carbon of successive monomeric units on alternate sides of a hypothetical plane through the main chain of the polymer. Syndiotactic polypropylene is clear, that is it does not have the lack of clarity characteristic of isotactic polypropylene.
There are two types of syndiotactic polypropylene. One of these types is referred to as being made by a chain-end control mechanism and contains defects of the rmr type. NMR analysis for this kind of structure is shown in Zambelli, et al., Macromolecules, 13, 267-270 (1980). The most syndiospecific polypropylene of this type made before this invention has [rrrr] pentad content of 0.63 (described in Pellecchia, C., et al., Macromol. Rapid Commun. 17, 333-338 (1996)) which limits the usage since the lower the [rrrr] pentad content, the lower the melting point. For example, a container made from polypropylene with [rrrr] pentad content of 0.63 will melt on contact with boiling water and thus is unuseful for containers for hot liquids. We turn now to the other type of syndiotactic polypropylene. It is referred to as being made by a site-control mechanism and as containing defects of the rmmr type. This type of polypropylene is described in European Patent Application Publication 0351391 A2 (published Jan. 17, 1990). Highly syndiotactic polypropylene ([rrrr]=0.97) has been made by a site-control mechanism. See Ewen, J. A., et al., J. Am. Chem. Soc., 110, 6255-6256 (1988), Herzog, T. A., et al., J. Am. Chem. Soc. 118, 11988-11989 (1996), and Veghini, D., et al., J. Am. Chem. Soc. 121, 564-573 (1999). This kind of syndiotactic polypropylene has not yet been commercialized apparently because of processing and/or economic factors.
It has been discovered herein that highly syndiospecific polypropylene can be made by a chain-control mechanism by utilizing certain bis(salicylaldiminato)titanium complex compounds as catalysts as well as block copolymers containing block(s) of the syndiotactic polypropylene and block(s) of poly(ethylene-co-propylene) and/or poly(alpha-olefin-co-propylene) and that living polymerization can be obtained and that certain of the catalysts are useful in the production of olefin terminated polymers and oligomers from propylene.
The invention herein in one embodiment, denoted the first embodiment, is directed to a bis(salicylaldiminato)titanium complex having the structure: 
where R is selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups, C1-C6 branched or straight chain alkoxide groups, and C1-C6 branched or straight chain amido groups, R1 is phenyl substituted with C1-C6 branched or straight chain alkyl group or electron withdrawing atom or group at the 2-position and optionally substituted with C1-C6 branched or straight chain alkyl groups or electron withdrawinig atom or group at one or more of the 3-, 4-, 5- and 6-positions, or is C1-C10 branched, cyclic or straight chain alkyl group, and R2 and R3 are the same or different and are selected from the group consisting of C4-C6 tertiary alkyl groups; or cationic form thereof The complexes are useful as catalysts for polymerization of olefins and are especially useful for polymerization of propylene.
The invention herein in another embodiment, denoted the second embodiment, is directed to syndiotactic polypropylene having Mw ranging from 10,000 to 500,000 and defects of the type rmr and [rrrr] pentad content greater than 0.70. The syndiotactic polypropylene is useful, for example, for packaging and container functionality.
The invention herein in another embodiment, denoted the third embodiment, is directed to syndiotactic poly(C4-C6-alpha olefins) having a Mw ranging from 10,000 to 500,000 and Mw/Mn ranging from 1.0 to 2.0. These syndiotactic polyolefins are useful for films and sheets because of their flexibility and transparency.
The invention herein in another embodiment, denoted the fourth embodiment, is directed to a method of preparing syndiotactic polypropylene having Mw ranging from 10,000 to 500,000 and defects of the type rmr and [rrrr] pentad content greater than 0.50 comprising polymerizing propylene dissolved in an aprotic solvent in the presence of a catalytically effective amount of a complex having the structure: 
where R is selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups, C1-C6 branched or straight chain alkoxide groups, and C1-C6 branched or straight chain amido groups, R1 is phenyl optionally substituted with one to five C1-C6 branched or straight chain alkyl groups or one to five electron withdrawing atoms or groups, or is C1-C10 branched, cyclic or straight chain alkyl group, and R2 and R3 are the same or different and are selected from the group consisting of H or C1-C6 branched or straight chain alkyl group, and an activating effective amount of compound that converts titanium of the complex to cationic form. The syndiotactic polypropylene product has packaging and container functionality.
The invention herein in still another embodiment, denoted the fifth embodiment, is directed to olefin terminated polymers and oligomers of propylene having the structure: 
where n ranges from 1 to 750. These compounds are useful, for example, to add as so-called xe2x80x98macromonomersxe2x80x99 to other polymerizations and can be incorporated about as well as hexene.
The invention in another embodiment denoted the sixth embodiment is directed to a method of preparing polymers and oligomers of propylene having the structure (II) where n ranges from 1 to 750 comprising polymerizing propylene in an aprotic solvent in the presence of a catalytically effective amount of complex having the structure (I) where R is selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups, C1-C6 branched or straight chain alkoxide groups, and C1-C6 branched or straight chain amido groups, R1 is phenyl optionally substituted at one or more of the 3-, 4-, and 5-positions but not at the 2- and 6-positions, the optional substitution at one or more of the 3-, 4- and 5-positions being with C1-C6 branched or straight chain alkyl group or electron withdrawing atom or group, and R2 and R3 are the same or different and are selected from the group consisting of H and C1-C6 branched or straight chain alkyl groups and an activating effective amount of compound that converts titanium of the complex to cationic form, and quenching the reaction when olefin-terminated polymer or oligomer of desired number of monomer units is formed.
The invention herein in still another embodiment, denoted the seventh embodiment, is directed to block copolymer having Mw ranging from 10,000 to 500,000 comprising at least one block of syndiotactic polypropylene and at least one block of poly(ethylene/propylene) where the ethylene content ranges from 1 to 100% by weight, containing a volume fraction of syndiotactic polypropylene ranging from 0.20 to 0.99. Species include block copolymer consisting essentially of one block of syndiotactic polypropylene and one block of poly(ethylene-co-propylene), block copolymer consisting essentially of a block of syndiotactic polypropylene followed by a block of poly(ethylene-co-propylene) followed by a block of syndiotactic polypropylene, and block copolymer consisting essentially of a block of syndiotactic polypropylene followed by a block of poly(ethylene-co-propylene) followed by a block of syndiotactic polypropylene followed by a block of poly(ethylene-co-propylene) followed by a block of syndiotactic polypropylene.
The invention in still another embodiment, denoted the eighth embodiment is directed to block copolymer having Mw ranging from 10,000 to 500,000 comprising at least one block of syndiotactic polypropylene and at least one block of poly(alpha-olefin/propylene), e.g., poly(C4-C6 alpha-olefin/propylene), e.g., poly(1-butene/propylene) where the alpha-olefin content (not propylene) ranges from 1 to 100% by weight, containing a volume fraction of syndiotactic polypropylene ranging from 0.20 to 0.99.
Chain-end control and defects of the type rmr as referred to herein are described in Coates, G. W., Chem. Rev. 100, 1223-1252 (2000).
The [rrrr] pentad contents described herein are measured as described in Resconi L., et al., Chem. Rev. 100, 1253-1345 (2000).
The term xe2x80x9celectron withdrawing atom or groupxe2x80x9d is used herein to mean atom or group where the connecting atom of the atom or group is more electronegative than hydrogen,
The term xe2x80x9cMwxe2x80x9d is used herein to mean weight average molecular weight, and the term xe2x80x9cMnxe2x80x9d is used herein to mean number average molecular weight and these are determined using gel permeation chromatography (GPC) in 1,2,4-trichlorobenzene at 140xc2x0 C. versus polystyrene standards, unless otherwise stated.
We turn now to the first embodiment of the invention which is directed to a bis(salicylaldiminato)titanium complex having the structure: 
where R is selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups, C1-C6 branched or straight chain alkoxide groups and C1-C6 branched or straight chain amido groups, R1 is phenyl substituted with C1-C6 branched or straight chain alkyl group or electron withdrawing group at the 2-position and optionally substituted with C1-C6 branched or straight chain alkyl group or electron withdrawing atom or group at one or more of the 3-, 4-, 5- and 6-positions, or is C1-C10 branched, cyclic or straight chain alkyl group, and R2 and R3 are the same or different and are selected from the group consisting of C4-C6 tertiary alkyl groups; or cationic form thereof.
R is described in conjunction with formula (I) as being selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups and C1-C6 branched or straight chain alkoxide groups and C1-C6 branched or straight chain amido groups. The halogen atoms include, for example, chlorine, fluorine and bromine atoms. The C1-C6 branched or straight chain alkyl groups include, for example t-butyl groups. In the compounds synthesized in the working examples, R is a chlorine atom.
R1 is described in conjunction with formula (I) as being phenyl substituted with C1-C6 branched or straight chain alkyl group or electron withdrawing atom or group at the 2-position and optionally substituted with C1-C6 branched or straight chain alkyl group or electron withdrawing atom or group at one or more of the 3-, 4-, 5- and 6-positions, or is C1-C10 branched, cyclic or straight chain alkyl group. The C1-C6 branched or straight chain alkyl groups include, for example, t-butyl. The electron withdrawing groups include, for example, fluorine atoms, nitro groups, trifluoromethyl groups, cyanide groups, and aldehyde groups. In Example X hereinafter, compounds of the formula (I) with R1 being phenyl substituted at least at the 2-position with fluoro were found to catalyze living polymerization of propylene as shown by Mw/Mn in the range of 1.0 to 1.35, and compounds of the formula (I) with R1 being phenyl substituted with fluoro at least at the 2- and 6-positions were found to catalyze polymerization of propylene to give syndiotactic polypropylene with Mw/Mn in the range of 1.0 to 1.35 and defects of the type rmr and [rrrr] pentad content greater than 0.70. In Example X, compound of the formula (I) with R1 being phenyl substituted with fluoro at the 2-, 3-, 4-, 5- and 6-positions, was found to catalyze polymerization of propylene to give syndiotactic polypropylene with Mw/Mn in the range of 1.0 to 1.35, i.e., living polymerization, and defects of the type rmr and [rrrr] pentad content of at least 0.95.
R2 and R3 are described in conjunction with formula (I) as being the same or different and as being selected from the group consisting of C4-C6 tertiary alkyl groups. R2 and R3 being C4-C6 tertiary alkyl group was found to be advantageous in respect to catalyzing polymerization of propylene to give syndiotactic polypropylene compared to where one of R2 and R3 is H in providing higher activity and higher M as indicated by a comparison of results for A and H in Table II of Example X hereinafter.
In several cases represented herein, the complexes have C-2 symmetry, i.e., both Rs are the same, both R1s are the same, both R2s are the same, and both R3s are the same.
Cationic form of the complex is referred to. This is the form active to catalyze polymerization. As indicated later, the complex can be converted to cationic form by co-catalyst that converts titanium of the complex to cationic form, e.g., when R is chlorine, an aluminum-containing co-catalyst can be used to pull off both chlorines and convert one to methyl or where R is alkyl, the co-catalyst [Ph3C][B(C6F5)4] can be used to abstract one alkyl.
Complexes of the formula (I) synthesized in the working examples have the structural formula: 
where R1, R2 and R3 are defined as in Table I below:
In Table 1, cC6H11 means cyclohexyl.
Complexes D, E, F and G of Table I are embraced by the first embodiment of the invention herein and complexes A, B, C, H and I are not embraced by the first embodiment of the invention herein.
The complexes of the formula (I) can be synthesized by reaction of 3-R2, 5-R3-salicylaldehyde, e.g., 3,5-di-tert-butylsalicylaldehyde where R2 and R3 are to be t-butyl and 3-tert-butylsalicylaldehyde where R2 is to be t-butyl and R3 is to be H, with aniline or substituted aniline or cyclohexylamine where the substituents provide the substituents on phenyl of R1, e.g., 2-fluoroaniline where R1 is to be 2-fluorophenyl, to obtain a ligand, and reacting the ligand with Ti(R)4, e.g., Ti(Cl)4 where R is to be Cl, in the presence of n-butyllithium and then isolating by crystallization. Where three or more fluorine substituents are on aniline reactant, the aniline reactant needs to be activated by forming the N-sulfinyl derivative of the fluoroaniline which is then reacted with the 3-R2, 5-R3-salicylaldehyde, e.g., N-sulfinyl-2,4,6-trifluoroaniline is used to obtain R1 which is 2,4,6-trifluorophenyl. The N-sulfinyl derivative is formed by refluxing the fluoroaniline with thionyl chloride. Specific reactions are set forth in working examples I, II, III, IV, V, VI, VII, VIII and IX, later herein.
In the above description of the first embodiment of the invention, compounds of the formula (I) are said to catalyze living polymerization of propylene. This means that the more of the monomer that is present, the longer the polymer obtained. The polymerization continues in this fashion until reactant is used up or the reaction is quenched by knocking the metal of the catalyst from the end of the polymer. The obtaining of living polymerization is shown by a low Mw/Mn, e.g., Mw/Mn ranging from 1.0 to 1.35. Living polymerization provides syndiotactic polypropylene without olefin end group.
We turn now to the second embodiment of the invention, which is directed to syndiotactic polypropylene having Mw ranging from 10,000 to 500,000 and defects of the type rmr and [rrrr] pentad content greater than 0.70. The polymer is made by a chain-end control mechanism since defects of the type rmr are recited. In one subgroup, the syndiotactic polypropylene has [rrrr] pentad content of at least 0.95. In another subgroup which can be overlapping with the first subgroup, Mw/Mn ranges from 1.05 to 1.35 and in products made in working examples ranges from 1.06 to 1.34. The syndiotactic polypropylene of this embodiment is made by the method of the fourth embodiment described below except that complex D of Table 1 is excluded as the catalyst. Details of synthesis are presented in working Example X which is set forth later. It is noted that some publications refer to [r] instead of [rrrr] pentad content; [r] to the fourth power gives [rrrr] pentad content for chain-end control statistics. Synthesis of the syndiotactic polypropylene of this embodiment can be carried out by the method of the fourth embodiment herein as described in conjunction with catalysis by complexes providing [rrrr] pentad content greater than 0.70.
We turn now to the third embodiment, which is directed to syndiotactic poly(C4-C6-alpha-olefins) having a Mw ranging from 10,000 to 500,000 and Mw/Mn ranging from 1.0 to 2.0, e.g., 1.0 to 1.5. The polymers are made by a chain-end control mechanism when defects of the type rmr are present. The alpha-olefins which are polymerized to prepare the syndiotactic poly(C4-C6-alpha-olefins) of this embodiment include, for example, 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene. These polymers can be prepared by polymerizing the alpha-olefin in an aprotic solvent, e.g., toluene or hexanes, in the presence of catalytically effective amount of complex of formula (I) where R is chlorine, R1 is phenyl substituted with fluoro at least at the 2- and 6-positions and R2 and R3 are t-butyl and an activating effective amount of compound that converts titanium of the complex to cationic form as described in conjunction with the fourth embodiment, preferably an aluminum-containing compound that converts titanium of the complex to cationic form. The polymerization is appropriately carried out at 0xc2x0 C. Aluminum-containing activator compounds include, for example, methyl aluminoxane (MAO) and polymethyl aluminoxane (PMAO) (which is more soluble than methyl aluminoxane in the aprotic solvent and thus more readily stays in solution). The amount of complex of formula (I) ranges from 0.2 to 20 mmol per 1,000 ml of solution of olefin on an olefin saturated solution basis. The aluminum-containing compound activator is used in a [Al]/[Ti] (the Ti being the Ti in the complex of formula (I)) ratio ranging from 10 to 1,000.
We turn now to the fourth embodiment of the invention, which is directed to a method of preparing syndiotactic polypropylene having a Mw ranging from 10,000 to 500,000 and defects of the type rmr and [rrrr] pentad content greater than 0.50 comprising polymerizing propylene dissolved in an aprotic solvent (preferably as a saturated solution) in the presence of a catalytically effective amount of complex: 
where R is selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups, C1-C6 branched or straight chain alkoxide groups, and C1-C6 branched or straight chain amido groups, R1 is phenyl optionally substituted with one to five C1-C6 branched or straight chain alkyl groups or one to five electron withdrawing atoms or groups, or is C1-C10 branched, cyclic or straight chain alkyl group, and R2 and R3 are the same or different and are selected from the group consisting of H or C1-C6 branched or straight chain alkyl groups, and an activating effective amount of compound that converts titanium of the complex to cationic form. The aprotic solvent can be, for example, toluene or hexanes, and is preferably toluene. The complex can be prepared as described above and is used in an amount from 0.2 to 20 mmol per 1,000 ml of solution of olefin (on an olefin saturated solution basis). The compound that converts titanium of the complex to cationic form is, for example, an aluminum-containing compound. When the complex used is one where both Rs are chlorine, the aluminum-containing compound functions by pulling both chlorines from the complex and converting one to methyl. Another compound that converts titanium of the complex to cationic form is [Ph3C][B(C6F5)]4; when complex is used where both Rs are alkyl, this co-catalyst abstracts one alkyl. A class of compounds that converts titanium of the complex to cationic form are clays. An aluminum-containing compound for use to convert titanium of the complex to cationic form preferably is methyl aluminoxane (MAO), very preferably polymethyl aluminoxane (PMAO) which is available from Akzo Nobel. The amount of aluminum-containing compound used ranges from 10 to 1,000 on a [Al]/[Ti] basis. Reaction temperature can range, for example, from xe2x88x9220 to 100xc2x0 C. and is preferably 0xc2x0 C. and reaction times can range, e.g., from 1 hour to 50 hours. Syndiotactic polypropylene with [rrrr] pentad content greater than 0.70 is obtained using complex of formula (I) as described above in conjunction with this embodiment, except for complex D of Table I. Syndiotactic polypropylene with Mw/Mn in the range of 1.0 to 1.35 and living polymerization are obtained using complex of formula (I) as described above in conjunction with this embodiment where R1 is phenyl substituted at least at the 2-position with fluorine. The reaction can be carried out, for example, at 01 to 300 psi and is carried out at 40 psi at 0xc2x0 C. in Example X hereinafter. In living or other polymerization, the polymerization can be ended when desired by knocking the metal of the catalyst off the end of the product, e.g., by quenching by injection of methanol/HCl (10% by volume HCl) in amount of from 1 to 10 volume percent of the polymerization solution.
We turn now to the fifth embodiment of the invention, which is directed to olefin terminated polymers and oligomers of propylene having the structure: 
where n ranges from 1 to 750. In the formula (II), n is the number of propylene units in the polymer or oligomer except for the olefin terminating end groups. Specific examples of this embodiment have the formula (II), where n=1, 2, 3, 4, 10, 20, 50 or 100. These polymers and oligomers are prepared by a method comprising polymerizing propylene in a method which does not give living polymerization, e.g., in the method of the sixth embodiment of the invention described below.
We turn now to the sixth embodiment of the invention which is directed to a method of preparing polymers and oligomers of propylene having the structure (II) where n ranges from 1 to 750 comprising polymerizing propylene in an aprotic solvent, preferably as a saturated solution, in the presence of a catalytically effective amount of complex having the structure (I) where R is selected from the group consisting of halogen atoms, C1-C10 branched or straight chain alkyl groups, C1-C6 branched or straight chain alkoxide groups, and C1-C6 branched or straight chain amido groups, R1 is phenyl optionally substituted at one or more of the 3-, 4-, and 5-positions but not at the 2- and 6-positions, the optional substitution at one or more of the 3-, 4- and 5-positions being with C1-C6 branched or straight chain alkyl group or electron withdrawing atom or group, and R2 and R3 are the same or different and are selected from the group consisting of H and C1-C6 branched or straight chain alkyl groups and an activating effective amount of compound that converts titanium of the complex to cationic form, and quenching the reaction when olefin-terminated polymer or oligomer of desired number of monomer units is formed.
The aprotic solvent can be, for example, toluene or hexanes and preferably is toluene. The complex and synthesis thereof is described above. Suitable complexes for use in this embodiment include complexes A, H and I of Table I above. The amount of said complex which is a catalytically effective amount ranges from 0.2 to 20 mmol per 1,000 ml of solution of propylene (on a propylene saturated solution basis). The compound that converts titanium of the complex to cationic form is the same as that described above in conjunction with the fourth embodiment of the invention herein. When the compound that converts titanium of the complex to cationic form is an aluminum-containing complex, it is preferably MAO, very preferably PMAO, used in an activating effective amount, for example, from 10 to 1,000 on a [Al/Ti] basis. Reaction temperature can range, for example, from xe2x88x9220 to 100xc2x0 C. and preferably is 0xc2x0 C., and reaction time can range, for example, from 1 hour to 50 hours. The reaction is quenched when desired amount of polymer is formed, e.g., by weighing solids in a sample and extrapolating to the whole reaction.
We turn now to the seventh embodiment of the invention, which is directed to block copolymer having Mw ranging from 10,000 to 500,000 comprising at least one block of syndiotactic polypropylene and one block of poly(ethylene/propylene) where the ethylene content ranges from 1 to 100% by weight, containing a volume fraction of syndiotactic polypropylene ranging from 0.20 to 0.99. The syndiotactic polypropylene is sometimes denoted SPP hereinafter. The poly(ethylene/propylene) is polyethylene, sometimes denoted PE hereinafter, when the ethylene content of the poly(ethylene/propylene) is 100% and otherwise is poly(ethylene-co-propylene), sometimes denoted EP hereinafter. In general the block polymers can be made by the methods for making syndiotactic polypropylene described hereinbefore but with sequential addition of monomers. The blocks of syndiotactic polypropylene preferably have [rrrr] pentad content greater than 0.70.
In one species of the seventh embodiment, there is provided a block copolymer having Mw ranging from 10,000 to 500,000 consisting essentially of one block of syndiotactic polypropylene and one block of poly(ethylene-co-propylene) where the volume fraction of syndiotactic polypropylene ranges from 0.20 to 0.99. This block copolymer may be referred to as a diblock. This block copolymer can be made as follows: The method for fourth embodiment is used initially where the complex used as catalyst is one that gives living polymerization, e.g., complexes B, C, D, E, F and G in Table I. In the reaction, the aprotic solvent is preferably saturated with propylene gas under a pressure ranging from 1 to 200, e.g., 40 psi. After the initial reaction whereby syndiotactic polypropylene is produced, ethylene at an overpressure of 1 to 10 psi compared to residual propylene pressure, is introduced and reaction proceeds to add a block of poly(ethylene-co-propylene). After a desired diblock is obtained, the reaction may be quenched, e.g., by injection of methanol/10 volume percent HCl, and product is recovered by precipitation and purification. Diblock of this type is made in Example X hereafter and is the 16th entry in Table II of Example X. The volume fraction of SPP in the diblock obtained in Example X was 0.26.
In a second species of the seventh embodiment, there is provided a block copolymer having a Mw ranging from 10,000 to 500,000 consisting essentially of a block of syndiotactic polypropylene followed by a block of poly(ethylene-co-propylene) followed by a block of syndiotactic polypropylene, where the volume fraction of syndiotactic polypropylene ranges from 0.20 to 0.99. This block copolymer may be referred to as a triblock. This block copolymer can be made the same as the diblock as described in the paragraph directly above, except that after the desired amount of formation of block of poly(ethylene-co-propylene), the ethylene feed is discontinued and the reaction consumes residual ethylene whereupon there is reversion to polymerization of propylene for the final block. Triblock of this type is made in Example X in three runs as indicated by the seventeenth, eighteenth and nineteenth entries in Table II of Example X. The volume fraction of SPP in the triblock of the seventeenth entry of Table II was 0.81 which gives a stiff characteristic. The volume fractions of SPP in the triblocks of the eighteenth and nineteenth entries of Table II were respectively 0.31 and 0.30 which provides an elastomeric regime since the EP block dominates.
In a third species of the seventh embodiment, there is provided a block copolymer having a Mw ranging from 10,000 to 500,000 consisting essentially of a block of syndiotactic polypropylene followed by a block of poly(ethylene-co-propylene) followed by a block of syndiotactic polypropylene followed by a block of poly(ethylene-co-propylene) followed by a block of syndiotactic polypropylene, where the volume fraction of syndiotactic polypropylene ranges from 0.20 to 0.99. This block copolymer may be referred to as a pentablock. This block copolymer can be made the same as the triblock as described in the paragraph directly above, except that the propylene polymerization is interrupted twice by the addition of ethylene.
The block copolymers containing polyethylene block(s) can be made the same as the block copolymers containing block(s) of poly(ethylene-co-propylene) as described above, except for the ethylene being introduced at higher pressure if propylene is present, e.g., 200 psi, so PE blocks are formed instead of EP blocks. Alternatively, the propylene can be allowed to be consumed and the ethylene introduced at low pressure, e.g., 5 psi. Structures made in this way include SPP-EP-PE triblock, SPP-EP-PE-EP-SPP pentablock, PE-EP-SPP-EP-PE pentablock, and PE-EP-PE triblock.
We turn now to the eighth embodiment of the invention herein which is directed to block copolymer having Mw ranging from 10,000 to 500,000 comprising at least one block of syndiotactic polypropylene and at least one block of poly(alpha-olefin/propylene), e.g., poly(C4-C6 alpha-olefin/propylene), e.g., poly(1-butene/propylene), where the alpha-olefin content (not propylene) ranges from 1 to 100% by weight, containing a volume fraction of syndiotactic polypropylene ranging from 0.20 to 0.99. The term alpha-olefin is used in the description of this embodiment to mean alpha-olefin different from propylene and is preferably C4-C6-alpha-olefin and includes 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene. In general, the block copolymers can be made by the methods for making syndiotactic polypropylene described hereinbefore but with sequential addition of monomers, i.e., analogous to the way block copolymers of SPP and EP are made.